A typical fuel supply system for a port fuel injected internal combustion engine includes an electric fuel pump that conveys fuel being stored in a fuel tank through a fuel supply line to a fuel injector on the engine. As the engine operates, the fuel pump is activated to provide a continuous supply of fuel to the engine. However, an engine's fuel consumption varies greatly with its required output. In order to ensure that the engine is always provided with adequate fuel, the electric fuel pump is typically designed to provide fuel to the engine at the rate required for maximum engine output. More fuel is required during times of higher engine demand and less fuel during times of lesser engine demand, or during idling. Such low pressure fuel systems have incorporated passive accumulators to accumulate excess fuel supplied by the electric fuel pump during times of non-peak engine output.
While these accumulators in port fuel injection systems work for their intended purpose, they are passive accumulators associated with low pressure fuel systems. Such accumulators are not in direct fluid communication with the fuel injectors and are not associated downstream of a positive displacement pump on the high pressure side of a direct injection fuel system. As a result, these typical accumulator arrangements are not effective for directly supplying pressurized fuel to the injectors of a direct injection system, which can be advantageous during a restart of a start-stop direct injection engine system. Further, such conventional accumulators in the low pressure PFI fuel systems with electric fuel pumps are not capable of harvesting pressurized fuel during engine shutdown after a key-off event.